DSpace Colección:http://hdl.handle.net/10045/101908
Sun, 07 Jun 2020 10:30:10 GMT2020-06-07T10:30:10ZPollutant emissions during the pyrolysis and combustion of starch/poly(vinyl alcohol) biodegradable filmshttp://hdl.handle.net/10045/107135
Título: Pollutant emissions during the pyrolysis and combustion of starch/poly(vinyl alcohol) biodegradable films
Autor/es: Moltó Berenguer, Julia; López-Sánchez, B.; Domene-López, Daniel; Moreno, A.I.; Font, Rafael; Montalbán, Mercedes G.
Resumen: The massive use of petroleum-based polymers and their improper waste treatment has brought on significant global environmental problems due to their non-biodegradable nature. Starch/poly(vinyl alcohol) (PVA) bioplastics are suitable substitutes for conventional polymers, such as polyethylene, due to their full biodegradability and excellent mechanical properties. Knowledge of the pollutant emissions during pyrolysis and combustion of starch/PVA films is important because they can arrive at landfills mixed with conventional polymers and be thermally degraded in uncontrolled fires. On the other hand, controlled thermal treatments could result in thermal valorization of the waste. Pyrolysis and combustion experiments were carried out at 650, 750, 850 and 950 °C in a laboratory furnace. The analysis of carbon oxides, light hydrocarbons, and semivolatile compounds, including polycyclic aromatic hydrocarbons (PAHs), is shown. Experiments showed lower pollutant emissions than those found with conventional polymers, such as polyethylene and polyester, in the same equipment. Nevertheless, the pyrolysis run at 950 °C showed the highest light hydrocarbon yield (123013 mg kg−1), but this is considerably lower than the values found for polyethylene. The main semivolatile compounds (not PAHs) emitted, with maximum yields ranging from 1351 to 4694 mg kg−1, were benzaldehyde, phenol, indene, and acetophenone. Specifically, the total semivolatile compounds emitted after pyrolysis and combustion of starch/PVA samples represent only 38 and 50%, respectively, of those emitted with polyethylene. Further, the main PAHs were naphthalene, acenaphthylene, and phenanthrene with maximum values of 4694, 2704 and 1496 mg kg−1, respectively. The PAH yield was considerably higher in experiments with low oxygen content.Thu, 01 Oct 2020 00:00:00 GMThttp://hdl.handle.net/10045/1071352020-10-01T00:00:00ZHeterogeneous Fenton Degradation of Patulin in Apple Juice Using Carbon-Encapsulated Nano Zero-Valent Iron (CE-nZVI)http://hdl.handle.net/10045/107151
Título: Heterogeneous Fenton Degradation of Patulin in Apple Juice Using Carbon-Encapsulated Nano Zero-Valent Iron (CE-nZVI)
Autor/es: Silwana, Notemba; Calderón Roca, Blanca; Ntwampe, Seteno Karabo Obed; Fullana, Andres
Resumen: Patulin (PAT), a mycotoxin found mainly in matured apples, is produced by different species of fungi, mainly Penicillium expansum, and is found in various fruits and vegetables used to produce juice. Little focus has been placed on nano-technological methods for the mitigation of this problem. In this work, carbon-encapsulated nano-zero valent iron (CE-nZVI) particles were synthesized and used as heterogeneous Fenton agents for the degradation of PAT in apple juice. The particles were found to have a spherical shape with a diameter of 130 ± 50 nm. In a heterogeneous Fenton degradation (involving CE-nZVI) process, a concentration of 0.05 g/L CE-nZVI with 0.5 mM H2O2 was used. Since the Fenton oxidation process is pH-dependent, placebo degradation was observed at varying pH conditions with an average percentage of PAT degradation of 27.8%, 87.0%, 98.0%, and 99.75% at pH 6, 5, 4.5, and 3.5 respectively, between 1 min to 4 h in a water matrix. In a juice matrix, at the regular pH of juice (3.6), percentage PAT degradation of 72% and 89% was obtained after a 2-h treatment using heterogeneous Fenton oxidation (CE-nZVI/H2O2) systems, using 0.5 mM H2O2 and 1 mM H2O2, respectively.Sun, 24 May 2020 00:00:00 GMThttp://hdl.handle.net/10045/1071512020-05-24T00:00:00ZKinetics of the Catalytic Thermal Degradation of Sugarcane Residual Biomass Over Rh-Pt/CeO2-SiO2 for Syngas Productionhttp://hdl.handle.net/10045/106668
Título: Kinetics of the Catalytic Thermal Degradation of Sugarcane Residual Biomass Over Rh-Pt/CeO2-SiO2 for Syngas Production
Autor/es: Quiroga, Eliana; Moltó Berenguer, Julia; Conesa, Juan A.; Valero, Manuel F.; Cobo, Martha
Resumen: Thermochemical processes for biomass conversion are promising to produce renewable hydrogen-rich syngas. In the present study, model fitting methods were used to propose thermal degradation kinetics during catalytic and non-catalytic pyrolysis (in N2) and combustion (in synthetic air) of sugarcane residual biomass. Catalytic processes were performed over a Rh-Pt/CeO2-SiO2 catalyst and the models were proposed based on the Thermogravimetric (TG) analysis, TG coupled to Fourier Transformed Infrared Spectrometry (TG-FTIR) and TG coupled to mass spectrometry (TG-MS). Results showed three different degradation stages and a catalyst effect on product distribution. In pyrolysis, Rh-Pt/CeO2-SiO2 catalyst promoted reforming reactions which increased the presence of H2. Meanwhile, during catalytic combustion, oxidation of the carbon and hydrogen present in biomass favored the release of H2O, CO and CO2. Furthermore, the catalyst decreased the overall activation energies of pyrolysis and combustion from 120.9 and 154.9 kJ mol−1 to 107.0 and 138.0 kJ mol−1, respectively. Considering the positive effect of the Rh-Pt/CeO2-SiO2 catalyst during pyrolysis of sugarcane residual biomass, it could be considered as a potential catalyst to improve the thermal degradation of biomass for syngas production. Moreover, the proposed kinetic parameters are useful to design an appropriate thermochemical unit for H2-rich syngas production as a non-conventional energy technology.Wed, 06 May 2020 00:00:00 GMThttp://hdl.handle.net/10045/1066682020-05-06T00:00:00ZNon-intentionally added substances (NIAS) in recycled plasticshttp://hdl.handle.net/10045/104010
Título: Non-intentionally added substances (NIAS) in recycled plastics
Autor/es: Horodytska, Oksana; Cabanes, Andrea; Fullana, Andres
Resumen: The demand for high quality recycled polymers in the European plastic industry is on the increase, likely due to the EU’s Plastic Strategy intended to implement the circular economy model in this sector. The problem is that there is not enough recycled plastic in the market. In terms of volume, post-consumer plastic waste could be key to meet the current and future demand. Nevertheless, a high level of contamination originated during the product’s life cycle restricts its use. The first step to change this must be identifying the undesired substances in post-consumer plastics and performing an effective risk assessment. The acquired knowledge will be fundamental for the development of innovative decontamination technologies. In this study, 134 substances including volatile and semi-volatile compounds have been identified in recycled LDPE and HDPE from domestic waste. Headspace and solvent extraction followed by GC/MS were used. The possible origin of each substance was studied. The main groups were additives, polymer and additives breakdown products, and contamination from external sources. The results suggest that recycled LDPE contains a broader number of additives and their degradation products. Some of them may cause safety concerns if reused in higher added value applications. Regarding recycled HDPE, the contaminants from the use phase are predominant creating problems such as intense odors. To reduce the number of undesired substances, it is proposed to narrow the variety of additives used in plastic manufacturing and to opt for separate waste collection systems to prevent cross-contamination with organic waste.Wed, 01 Jul 2020 00:00:00 GMThttp://hdl.handle.net/10045/1040102020-07-01T00:00:00Z